[vid]

You know who was really good at getting the classical proportions bang-on?

Ludwig Mies van der Rohe.

In Classical buildings, people came second to showy ornamentation. Considerable modifications are required, such as inventing a way to incorporate a garage into the proportion and symmetry of the style. The way we laid out rooms in our houses then is different than how we do today, because how we use houses has changed.

And PhotoLith is right, the chance of any building being decently proportioned and made with quality materials is pretty low.